Script /etc/sysconfig/network-scripts/ifup-ppp only partially processes
"DISCONNECTTIMEOUT" and "RETRYTIMEOUT" parameters. The options never get
passed to the ppp daemon. That is, they are never added to the '$opts'
variable as "idle ${DISCONNECTTIMEOUT}" and "holdoff ${RETRYTIMEOUT}" if
they are not null (which they never are, as they are defaulted at the
start of the script).